The present invention relates generally to projection television sets, and more particularly to an integrally weighted base that facilitates structural and operational stability in a projection television enclosure.
Projection televisions (PTVs) or xe2x80x9cbig screenxe2x80x9d TVs are a popular alternative to traditional picture tube televisions because they provide comparably larger viewable screens that cannot be efficiently produced using conventional picture tubes. PTV cabinets are presently designed to hold electrical and optical components, as required, to decipher and project a television picture on a screen generally on the front of the cabinet. The most common PTV on the market today projects pictures created via appropriate electrical and optical components onto a mirror within a box containing the entire apparatus so that the picture reflected to a screen is as large as possible for the volume occupied by the cabinet enclosing it. Currently, PTV screens typically range in size from about 45 to about 73 inches along their diagonal, while the cabinets typically range in size from about 48 inches to over 65 inches in height, from about 38 inches to over 65 inches in width, and from about 22 inches to over 29 inches in depth. The cabinets are assembled in an aesthetically appealing manner as required to hold the electrical components, light generator(s), and lenses, mirror and screen in the relationship required to obtain the desired televised picture.
Most PTVs marketed today include a cabinet constructed from multiple pieces of particleboard cut and glued together. Some cabinets also have plastic components held to the basic cabinet structure with screws or other fasteners. The number of plastic components and particleboard pieces needed to form such cabinets typically range in excess of fifty (50) pieces. Because of the size of PTVs, and the particleboard from which the cabinets are typically constructed, PTVs tend to be quite heavy and difficult to maneuver.
Alternative methods of manufacture are available that may reduce the overall weight of these cabinets and the number of components necessary to construct such cabinets. For instance, injection molding could be used to form such cabinets out of plastic. Another alternative would be to vacuum form the cabinetry out of plastic. A further alternative would be to form the cabinet out of molded plastic foam.
The use of lighter weight materials to manufacture PTV cabinets leads to an additional problem in that the newer, light weight cabinets are easier to tip over relative to the traditional particle board cabinets. For example, in addition to being lighter in weight, newer PTV cabinets are also increasingly shallower in depth relative to traditional cabinets. The shallower depth cabinets have a smaller footprint but still generally maintain the same height as traditional PTV cabinets. Consequently, tip over for the newer cabinets becomes more likely when compared with the traditional cabinets.
In order to ensure that they produce PTVs that are not likely to tip over, PTV manufacturers typically strive to meet certain safety standards with respect to PTVs and PTV enclosures. One current standard is the Underwriters Laboratories (xe2x80x9cULxe2x80x9d) load standard. The UL load standard requires that a PTV cabinet must be able to withstand 25 lbs of force applied to any extremity of the cabinet without tipping over. Without the addition of some weight to the lower portion of the lighter, shallower PTV cabinets, these cabinets are more likely to fail the UL tip over test when compared with traditional particle board cabinets. To address this problem, those skilled in the art currently add counterweights to the base or lower portions of the lighter weight and shallower cabinets in order to enable these cabinets to withstand at least 25 lbs of force applied to any of their extremities without tipping over. Using one example calculation, the total weight for a PTV cabinet to avoid tip over is determined using the following formula:
Minimum Weight=(25 lbs)(Height of the Cabinet/Depth of the Cabinet).
Turning to FIG. 1, a conventional enclosure 10 of a PTV 50 is illustrated. The conventional enclosure 10 includes top 12, bottom 14, front 16, and rear 18 panels. Side panels connecting the front 16 and rear 18 panels are also included, but not illustrated. The conventional enclosure 10 is typically divided by an internal wall 24 into two compartments, i.e., an upper 20 and a lower 22 compartment. Cathode ray tubes (CRTs) 26 and printed wiring boards (PWBs) 30 are typically mounted in the lower compartment 22, while a mirror M and a screen S are mounted in the upper compartment 20. At least one projection lens 28 typically extends from the lower compartment 22 into the upper compartment 20 through the internal wall 24. The upper compartment 20 is typically tightly sealed from the lower compartment 22 to protect the inside of the upper compartment 20 from dust and other foreign materials. The lower compartment 22 typically includes one or more sets of ventilation holes to exhaust heat radiating from the CRTs 26 and the PWBs 30. As shown, the lower compartment 22 may include a first set of ventilation holes 32 positioned adjacent the top of the lower compartment 22 and a second set of ventilation holes 34 positioned adjacent the bottom of the lower compartment 22. When the enclosure 10 is made shallower and/or is constructed using lighter weight materials and methods, such as those previously discussed, counterweights 36 are typically positioned in the lower compartment 22, and normally on top of the bottom panel 14. The counterweights 36 increase the enclosure""s total weight and lower the enclosure""s center of gravity. As a result, the counterweights 36 increase the amount of force required to tip over the enclosure 10. Currently, counterweights 36, which may be metal, clay, or concrete bricks, additional particle board base pieces, or any other suitable counterweights, are tied or otherwise physically attached to the bottom panel 14 of the enclosure 10. The number of counterweights 36 used in the cabinet 10, to enable the enclosure 10 to pass the UL tip over test, may be determined with the aforementioned formula.
The current methods for balancing a shallower, lighter PTV cabinet result in several disadvantages. For example, the use of additional particle board bases to increase the weight and stability of these cabinets often requires the additional use of forest products, thereby contributing to long term environmental deleterious effects. Also, the additional step of adding a separate weight to a cabinet increases the complexity and cost of manufacturing the lighter weight PTV cabinets. There is also a danger that the weights may not be properly secured to the cabinet during construction, thereby resulting in safety issues should the weights become dislodged during transport of the cabinet, or during the lifetime of the cabinet. For example, the weights may become dislodged and repositioned in an area that causes the cabinet to become unbalanced and more likely to tip over.
Those skilled in the art have failed to provide for a light weight PTV cabinet capable of passing standard load tests without the addition of costly counterweights. Thus, it would be desirable to provide for a PTV cabinet or an integrally weighted base suitable for attachment to a PTV cabinet that is easy and less costly to manufacture, mitigates environmental damage by decreasing the reliance on wood as a material for counterweights, is less vulnerable to manufacturing irregularities, and results in a cabinet that meets any applicable load or tip over standards for PTV cabinets.
The present invention is directed to an integrally weighted base for use with an enclosure to form an integrally weighted PTV cabinet. The base acts to stabilize the cabinet and enables the cabinet to satisfy load and tip over standards. The base of the present invention is particularly useful when implemented as part of a lighter weight PTV cabinet, but is also capable of being used with traditional, wood-based PTV cabinets.
In one embodiment, a base for attachment to a bottom of an enclosure, thereby forming a cabinet, is provided. The enclosure has a plurality of side panels that form a footprint. The base is configured to conform to the footprint of the enclosure. The base includes a frame that conforms to the footprint and fill material set within the frame. The fill material may be concrete, metal, a mixture of concrete and fiber, a mixture of concrete and metal, or any other suitable material. The frame may be metal, plastic, or any other suitable material. Additionally, the frame may be divided into a raised area with a top surface and a lower region adjacent the raised area. In this embodiment, the fill material is disposed within the lower region of the frame. A plurality of openings may also be provided on the top surface of the raised area, allowing for ventilation to facilitate the dissipation of heat from within the interior of a cabinet. Elevated portions having openings configured for receiving an attachment element may be provided within the lower region that allows for a component to be secured to the base.
In another embodiment, a base is provided that is formed from a hardened material conformed to the footprint of an enclosure. In this embodiment, the base does not include a separate frame. The base may be formed of metal, a mixture of concrete and fiber, or a mixture of concrete and metal. The base may be divided into a raised area having a top surface and a lower region adjacent the raised area. The top surface of the raised area may further include a plurality of ventilation openings allowing for heat dissipation.
Another embodiment of the present invention is a cabinet for a PTV having an enclosure with a mirror, a plurality of CRTs, a projection lens, and a plurality of panels, and a base attached to the enclosure. The enclosure preferably includes a top panel, a front panel, a rear panel, and side panels extending between the front and rear panels. Attached to the top portion, and opposite the top panel of the enclosure, is a base having a frame and fill material disposed in the frame. The base provides stability to the cabinet and enables the cabinet to satisfy standard load bearing requirements. The base may also include at least one raised area, each raised area having a top surface, at least one lower region adjacent to each raised area, and fill material deposited into each lower region. The top surface of the raised region may include a plurality of vent openings allowing heat built up within the enclosure to dissipate therethrough. In another embodiment, additional elevated regions are present on the base that allow for components to be securably attached to the base. The fill material is preferably a material sufficient to provide the necessary weight to the enclosure. Exemplary fill materials include concrete, a concrete and fiber mixture, a concrete and metal mixture, and a metallic material.
In another aspect of the present invention, a method of manufacturing an integrally weighted base suitable for attachment to an enclosure of a television cabinet is provided. A frame is manufactured that conforms to the footprint exhibited by the panels of the enclosure. The frame may be, for example, a sheet metal stamping, molded plastic, metal casting, or wood. A fill material, which may be, e.g., concrete, a concrete and fiber mixture, a concrete and metal mixture, or a metal substance, is poured into the frame and allowed to set or harden. To form a frameless base, a mold is formed that conforms to the footprint of the enclosure and a compound is poured into the mold and allowed to set. The fill material is allowed to set and is then abraded or ground such that the fill material forms a substantially flat surface. If the frame is divided into raised and lowered regions, the fill material is typically poured substantially within the lower regions of the base, although some fill material may accumulate atop the raised region. Here, after the fill material has set, the fill material is abraded or ground such that the fill material forms a substantially flat surface that is substantially level with the top surface of the raised region.
Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with accompanying drawings.